When the "Use entire disk" partitioning solution is chosen in a UEFI
install, any existing ESP will be deleted, so we must force the
partition suggestions to be updated to ensure we create a new one.

(this matches what is done in the diskdrake auto-allocate routine)

The compare function doesn't look at the filesystem type, so there's
no need to probe it.

This avoids unwanted udev events when we are checking that the kernel
has been informed of partition table changes.

If we are upgrading a system on a GPT disk and it doesn't currently
have a BIOS boot partition, the old system must be using a legacy
bootloader (e.g. grub). We support the continued use of legacy
bootloaders in an upgrade, so there is no need to insist on a BIOS
boot partition in this case.

This relaxes the rules in fs::any::is_boot_bios_part_needed to allow
the BIOS boot partition to be located on any disk, not just the disk
containing the root partition. It also ensures that a BIOS boot
partition is never forcibly required in a system with non-GPT disks.

This prevents misreporting of the partition type in diskdrake if they
located on top of an old partition that contained a valid file system.

When doing a UEFI install, we add a fstab entry to mount the ESP on
/boot/EFI. This is neither required nor desirable when doing a legacy
boot install, even if an ESP is present on the disk.

The subroutine isEmpty() is used to identify free space on the disk
(not DOS "Empty" partitions). Because we use a string to flag Empty
and BIOS_GRUB partitions, rather than a numeric value, the numeric
equality operator gives false positives.

To minimise the changes this close to mga6 release (and until we fix
the bug in partition auto-allocation that mistakenly creates BIOS boot
partitions non-GPT disks), reuse the BIOS_GRUB flag for flagging Empty
partitions, as the real partition ID (0x00) is used to flag free space.